{ "category": "Logical functions", "display_name": "IFERROR", "entry_kind": "built_in_function", "eval_api": { "method": "POST", "url": "https://handbook.dnacalc.com/api/eval" }, "function_id": "FUNC.IFERROR", "implementation_state": { "answer_bank": null, "detail": "Recorded: 95 workbook cells.", "dnacalc_commit": "9e1884369a678158dd82d3d74188daf986995e87", "in_catalogue": true, "state": "matches", "state_label": "Matches every recorded Excel answer", "summary": "Matches all 95 recorded answers", "workbook_corpus": { "cells": 95, "matched": 95 } }, "implementations": [ { "commit": "9e1884369a678158dd82d3d74188daf986995e87", "flavour": "excel-compatibility-candidate", "language": "Rust", "name": "CalcFunc", "own_code": [ "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/catalogue/error_fallback.rs#L33-L44", "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/catalogue/error_fallback.rs#L57-L67" ], "repository": "https://github.com/DnaCalc/DnaCalc", "shared_code": [ "catalogue/error_fallback::fallback_selected", "catalogue/error_fallback::not_scalar" ], "source": "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/catalogue/error_fallback.rs#L33-L44", "state": "matches", "suite": null, "summary": "Matches all 95 recorded answers" } ], "json_url": "https://handbook.dnacalc.com/api/functions/FUNC.IFERROR.json", "name": "IFERROR", "notes": [], "schema": "efh.function-reference/v1", "section_order": [ "what-it-does", "try-it", "quirks", "how-to-implement", "version-differences", "alternatives" ], "sections": { "alternatives": "\n### Relationships\n\n\n- **`IFNA`** is the surgical version: it masks `#N/A` only and lets every other error through. For\n lookup formulas this is almost always the right choice, and the pair `IFERROR`/`IFNA` is the\n clearest \"total versus selective\" contrast in the function library.\n- **`ISERROR`, `ISERR`, `ISNA`** are the inspection functions; `IF(ISERROR(x), y, x)` is the\n pre-2007 idiom `IFERROR` replaced, and it evaluates `x` twice. `ISERR` is `ISERROR` minus `#N/A`\n — the same distinction `IFNA` draws, from the other side.\n- **`AGGREGATE`** with the appropriate option skips errors inside an aggregation, which is the\n aggregate-shaped analogue of masking.\n- **`IF`** returns branch errors verbatim and is the function people wrongly expect to handle\n errors.\n- `IFERROR` arrived in Excel 2007. Workbooks that must open in Excel 2003 use the double-evaluation\n `IF(ISERROR(...))` idiom instead; that is a version-compatibility fact, not a\n Compatibility-category supersession, and Microsoft has not deprecated anything here.\n\n\n", "how-to-implement": "\n### Notes for implementers\n\n1. **Test the kind, not the code.** Any per-code logic belongs in `IFNA`, not here. If your\n `IFERROR` needs a list of error codes, the design has already gone wrong.\n2. **Do not evaluate the fallback eagerly.** The whole point of `IFERROR` over the `ISERROR` idiom\n is single evaluation of the primary and no evaluation of the fallback when it is not needed.\n3. **Decide the array policy explicitly and write it down.** Elementwise masking and whole-array\n masking give different answers for any array containing both errors and values, and this is\n exactly where a dynamic-array-era implementation will diverge from a legacy one.\n\n\n", "quirks": "\n### Result and edge cases\n\n\nReturns whatever kind the selected argument carries.\n\n- **Primary is not an error.** Returned verbatim, including text, logicals, and arrays.\n- **Primary is any error.** The fallback is returned, verbatim.\n- **Fallback is itself an error.** Returned as-is. `IFERROR(1/0, NA())` is `#N/A` — the mask does\n not iterate.\n- **Empty text as the primary.** `IFERROR(\"\", \"\")` is the empty string. Empty text is a perfectly\n good non-error value.\n- **Arrays.** The function's own classification is surface-native; an array primary containing a\n mix of errors and values raises the question of whether the mask applies elementwise or to the\n array as a whole. That question is listed below as unchecked, and it is the most consequential\n unknown on this page for modern dynamic-array formulas.\n\n\n\n### Errors\n\n\n| Error | Condition |\n|---|---|\n| any error | Only by being returned from `value_if_error`, or by propagating from a failure in preparing the arguments themselves. |\n\n", "sources": "- `data/functions/FUNC.IFERROR.json`, `data/presence/FUNC.IFERROR.json`.\n\n\n", "version-differences": "No comparison between specific Excel builds is recorded here yet. This does not establish that all builds behave alike.", "what-it-does": "\n`IFERROR(value, value_if_error)` returns `value` unless `value` is an **error value of any code**,\nin which case it returns `value_if_error`.\n\nThe test is on the *kind* of the value, not on its content: the function asks \"is this an `Error`?\"\nand nothing else. All fourteen worksheet error codes\n([chapter 01](../model/01-value-universe.md)) are masked equally — `#DIV/0!`, `#N/A`, `#VALUE!`,\n`#REF!`, `#NAME?`, `#NUM!`, `#NULL!`, and the extended family alike.\n\nThis is the crucial property and the crucial danger. `IFERROR` is a **total** mask: it cannot\ndistinguish a divide-by-zero you expected from a `#REF!` caused by a deleted column or a `#NAME?`\ncaused by a typo in the very formula it wraps. Wrapping a lookup in `IFERROR` to suppress \"not\nfound\" also suppresses every structural break in that lookup, silently and permanently. `IFNA`\nexists precisely because that trade is usually a bad one.\n\n`IFERROR` is one of the declared exceptions to the engine's universal error-propagation rule: the\ncoercion model states that errors propagate through conversion *unless* a family explicitly\ndeclares branching behaviour, and `IFERROR` is named as such a declaration\n([chapter 02](../model/02-coercion-and-lifting.md), \"Error propagation\").\n\nLike `IF`, it is a lazy selector — the fallback is only reached when the primary is an error.\n\n\n\n### Arguments\n\n\n`IFERROR(value, value_if_error)`\n\n- **`value`** — required. The expression to test. In practice this is the whole formula you wanted\n to write; `IFERROR` wraps it.\n\n\n" }, "signature": { "display": "IFERROR(value, value_if_error)", "parameters": [ { "description": null, "name": "value", "optional": false, "repeats": false }, { "description": null, "name": "value_if_error", "optional": false, "repeats": false } ], "trailing_repeats": false }, "sources": { "metadata": { "admission": { "label": "implemented", "reason": null }, "arity": { "max": 2, "min": 2 }, "category": "Logical functions", "classification": { "arg_preparation_profile": "RefsVisibleInAdapter", "coercion_lift_profile": "Custom", "determinism_class": "Deterministic", "error_collapse_profile": "SelectorBranch", "fec_dependency_profile": "None", "host_interaction_class": "None", "kernel_signature_class": "Custom", "rich_value_usage": "RichBlind", "surface_fec_dependency_profile": "RefOnly", "thread_safety_class": "SafePure", "volatility_class": "NonVolatile" }, "descriptions": { "long": null, "short": "The value of an expression, or a fallback when it is an error", "short_source": "dna-calc-own" }, "docs": { "english_description": "Returns a value you specify if a formula evaluates to an error; otherwise, returns the result of the formula", "microsoft_url": "https://support.microsoft.com/en-us/office/iferror-function-c526fd07-caeb-47b8-8bb6-63f3e417f611" }, "entry_kind": "built_in_function", "localized_family_names": null, "localized_names": [ { "locale": "ar-SA", "name": "IFERROR" }, { "locale": "bg-BG", "name": "IFERROR" }, { "locale": "cs-CZ", "name": "CHYBHODN" }, { "locale": "da-DK", "name": "HVIS.FEJL" }, { "locale": "de-DE", "name": "WENNFEHLER" }, { "locale": "el-GR", "name": "IFERROR" }, { "locale": "en-AU", "name": "IFERROR" }, { "locale": "en-GB", "name": "IFERROR" }, { "locale": "en-US", "name": "IFERROR" }, { "locale": "es-ES", "name": "SI.ERROR" }, { "locale": "et-EE", "name": "IFERROR" }, { "locale": "fi-FI", "name": "JOSVIRHE" }, { "locale": "fr-FR", "name": "SIERREUR" }, { "locale": "he-IL", "name": "IFERROR" }, { "locale": "hr-HR", "name": "IFERROR" }, { "locale": "hu-HU", "name": "HAHIBA:" }, { "locale": "id-ID", "name": "IFERROR" }, { "locale": "it-IT", "name": "SE.ERRORE" }, { "locale": "ja-JP", "name": "IFERROR" }, { "locale": "ko-KR", "name": "IFERROR" }, { "locale": "lt-LT", "name": "IFERROR" }, { "locale": "lv-LV", "name": "IFERROR" }, { "locale": "nb-NO", "name": "HVISFEIL" }, { "locale": "nl-NL", "name": "ALS.FOUT" }, { "locale": "pl-PL", "name": "JEŻELI.BŁĄD" }, { "locale": "pt-BR", "name": "SEERRO" }, { "locale": "pt-PT", "name": "SE.ERRO" }, { "locale": "ro-RO", "name": "IFERROR" }, { "locale": "ru-RU", "name": "ЕСЛИОШИБКА" }, { "locale": "sk-SK", "name": "Funkcia IFERROR" }, { "locale": "sl-SI", "name": "IFERROR" }, { "locale": "sr-Latn-RS", "name": "IFERROR" }, { "locale": "sv-SE", "name": "OMFEL" }, { "locale": "th-TH", "name": "IFERROR" }, { "locale": "tr-TR", "name": "EĞERHATA" }, { "locale": "uk-UA", "name": "IFERROR." }, { "locale": "vi-VN", "name": "IFERROR" }, { "locale": "zh-CN", "name": "IFERROR" }, { "locale": "zh-HK", "name": "IFERROR" }, { "locale": "zh-TW", "name": "IFERROR" } ], "signature": { "display": "IFERROR(value, value_if_error)", "parameters": [ { "description": null, "name": "value", "optional": false, "repeats": false }, { "description": null, "name": "value_if_error", "optional": false, "repeats": false } ], "trailing_repeats": false }, "surface_name": "IFERROR", "version_marker": null, "xlcall": { "code": "480", "symbol": "xlfIferror" } }, "microsoft": "https://support.microsoft.com/en-us/office/iferror-function-c526fd07-caeb-47b8-8bb6-63f3e417f611" }, "try_it": { "formula": "=IFERROR(1/0,\"fallback\")" }, "url": "https://handbook.dnacalc.com/functions/IFERROR.html", "variants": [], "versions": [] }